Chronic obstructive pulmonary disease (COPD) is a progressive and irreversible respiratory condition characterized by persistent airflow limitation due to chronic inflammation of the airways and lung tissue damage [1]. It encompasses conditions such as chronic bronchitis and emphysema, primarily caused by long-term exposure to irritants like tobacco smoke, air pollution, and occupational dusts and chemicals [2]. The disease leads to symptoms including shortness of breath, chronic cough, sputum production, wheezing, and frequent respiratory infections, which worsen over time and significantly impair quality of life. Diagnosis relies on clinical evaluation and spirometry, a pulmonary function test that measures forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC), with a post-bronchodilator FEV₁/FVC ratio < 0.7 confirming airflow obstruction [3]. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) system classifies COPD severity based on FEV₁ and symptom burden, guiding treatment strategies. Management includes smoking cessation, pharmacological therapies such as bronchodilators and inhaled corticosteroids, pulmonary rehabilitation, oxygen therapy for hypoxemia, and vaccination to prevent exacerbations [4]. Exacerbations, often triggered by infections or environmental factors, require prompt treatment with antibiotics, systemic corticosteroids, and sometimes non-invasive ventilation [5]. The disease burden is substantial, particularly in low- and middle-income countries, where indoor air pollution from biomass fuels contributes significantly. Public health efforts by organizations like the World Health Organization and the Pan American Health Organization focus on tobacco control, early detection, and improving access to care. Research into emerging therapies, including gene editing for alpha-1 antitrypsin deficiency and biologics targeting eosinophilic inflammation, offers hope for more personalized and effective treatments in the future.

Pathophysiology and Molecular Mechanisms

Chronic obstructive pulmonary disease (COPD) is characterized by persistent and progressive airflow limitation driven by chronic inflammation, structural remodeling of the airways, and destruction of lung parenchyma. The underlying pathophysiological processes involve a complex interplay of cellular and molecular mechanisms triggered primarily by long-term exposure to irritants such as tobacco smoke, air pollutants, and occupational dusts. These mechanisms lead to irreversible changes in lung architecture and function, culminating in clinical manifestations such as dyspnea, chronic cough, and sputum production [2].

Chronic Airway Inflammation and Immune Cell Activation

The hallmark of COPD is chronic inflammation affecting both the airways and the alveolar tissue. This inflammatory response is sustained by the recruitment and activation of various immune cells, including neutrophils, alveolar macrophages, and T lymphocytes, particularly CD8+ cytotoxic T cells [7]. Neutrophils infiltrate the airways in large numbers and release neutrophil elastase, a protease that degrades elastin and collagen in the lung parenchyma, contributing directly to emphysema development [8].

Alveolar macrophages are also significantly increased in COPD and play a central role in amplifying inflammation by producing pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-8 (CXCL8) [7]. IL-8 acts as a potent chemotactic agent for neutrophils, creating a self-perpetuating cycle of inflammation. Additionally, a relative deficiency in regulatory T cells (Tregs) impairs immune regulation, allowing unchecked inflammatory responses [10].

Cytokine Networks and Signaling Pathways

The inflammatory cascade in COPD is mediated by a network of cytokines and chemokines that activate intracellular signaling pathways such as nuclear factor-kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and Janus kinase-signal transducer and activator of transcription (JAK-STAT) [11]. These pathways regulate the expression of genes involved in inflammation, apoptosis, and tissue remodeling. For example, NF-κB activation leads to increased production of IL-8 and other inflammatory mediators, while MAPK signaling contributes to mucus hypersecretion and airway remodeling.

Oxidative Stress and Its Role in Tissue Damage

Oxidative stress is a key driver of COPD pathogenesis, resulting from an imbalance between reactive oxygen species (ROS) production and antioxidant defenses. Tobacco smoke contains high levels of free radicals that directly damage cellular components, including lipids, proteins, and DNA [12]. This oxidative burden also activates inflammatory signaling pathways such as NF-κB, further amplifying inflammation.

Moreover, ROS inactivate alpha-1 antitrypsin (AAT), reducing its ability to inhibit neutrophil elastase and thereby promoting uncontrolled proteolytic destruction of alveolar walls [13]. Oxidative stress also impairs ciliary function and epithelial integrity, contributing to mucus accumulation and recurrent infections. Biomarkers of oxidative damage, such as malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), are elevated in patients with COPD and correlate with disease severity [14].

Protease-Antiprotease Imbalance

One of the classical mechanisms in COPD is the disruption of the protease-antiprotease balance. Neutrophil elastase and other matrix metalloproteinases (MMPs) degrade structural proteins in the lung extracellular matrix, particularly elastin. In healthy individuals, this activity is counterbalanced by antiproteases such as AAT. However, in COPD, this equilibrium is disrupted due to increased protease release and/or decreased antiprotease activity.

In individuals with genetic alpha-1 antitrypsin deficiency (AATD), the lack of functional AAT leads to unchecked elastase activity, resulting in early-onset emphysema even in non-smokers [15]. In smoking-related COPD, oxidative inactivation of AAT further exacerbates this imbalance, accelerating parenchymal destruction [16].

Systemic Inflammation and Comorbidities

COPD is not confined to the lungs; it is associated with systemic inflammation characterized by elevated circulating levels of inflammatory markers such as C-reactive protein (CRP), fibrinogen, and IL-6 [17]. This low-grade systemic inflammation contributes to the development of comorbidities such as cardiovascular disease, osteoporosis, sarcopenia, and metabolic syndrome. The presence of systemic inflammation underscores the multisystem nature of COPD and highlights the importance of holistic management strategies.

Phenotypic Variability in Inflammatory Pathways

COPD is a heterogeneous disease with distinct clinical phenotypes that reflect differences in underlying molecular mechanisms. The emphysema-predominant phenotype is associated with greater parenchymal destruction, increased macrophage and CD8+ T cell infiltration, and pronounced oxidative stress [18]. In contrast, the chronic bronchitis phenotype features airway-centered inflammation with neutrophil infiltration, goblet cell hyperplasia, and mucus hypersecretion driven by upregulation of mucins such as MUC5AC and MUC5B [19].

A third important phenotype is eosinophilic inflammation, defined by elevated blood eosinophil counts (≥300 cells/μL). This phenotype is associated with a type 2 inflammatory response involving IL-5, IL-4, and IL-13, and is linked to a higher risk of exacerbations that respond to inhaled corticosteroids (ICS) [20]. The identification of eosinophilic inflammation has enabled more personalized treatment approaches, including the use of biologic therapies targeting IL-5 or its receptor [21].

The understanding of these molecular and cellular mechanisms has paved the way for targeted therapies, such as biologics for eosinophilic inflammation and gene editing approaches for AATD. Ongoing research into oxidative stress pathways and inflammatory mediators continues to refine our understanding of COPD heterogeneity and inform the development of precision medicine strategies.

Risk Factors and Epidemiology

Chronic obstructive pulmonary disease (COPD) is a major global health burden, with its prevalence and impact shaped by a complex interplay of environmental, genetic, and demographic factors. The disease is largely preventable, as most cases are attributable to modifiable risk factors, particularly tobacco smoke and environmental pollutants. Understanding the epidemiology and risk factors of COPD is essential for developing effective public health strategies and targeted interventions.

Primary Risk Factors

The most significant cause of COPD is tobacco smoking, which accounts for more than 70% of cases in high-income countries [22]. Cigarette smoke induces chronic inflammation in the lungs, leading to structural damage such as the destruction of alveoli and narrowing of airways. This process is driven by oxidative stress, impaired ciliary function, and protease-antiprotease imbalance [23]. Moreover, exposure to secondhand smoke (passive smoking) also increases the risk of developing COPD, underscoring the importance of smoke-free environments [2].

Beyond tobacco, long-term exposure to various environmental and occupational pollutants plays a critical role. In low- and middle-income countries, indoor air pollution from the combustion of biomass fuels—such as wood, charcoal, or agricultural waste—for cooking and heating in poorly ventilated homes is responsible for 30% to 40% of COPD cases [1]. This exposure disproportionately affects women, who often spend more time near domestic hearths [26].

Outdoor air pollution is another major contributor, with particulate matter (PM2.5, PM10), nitrogen dioxide (NO₂), and ozone linked to both the development and worsening of COPD symptoms [27]. Occupational exposure to dusts, vapors, and chemical fumes—common in industries such as mining, construction, and agriculture—also elevates the risk. Workers exposed to substances like silica dust or metal fumes face a 22% higher risk of developing COPD [28]. In Spain, it is estimated that 15% to 20% of COPD cases are attributable to occupational exposures [28].

Genetic and Biological Factors

A small but significant proportion of COPD cases are linked to genetic predispositions. The most well-characterized genetic condition is alpha-1 antitrypsin deficiency (AATD), an autosomal codominant disorder caused by mutations in the SERPINA1 gene [30]. This deficiency reduces levels of a protective protein that inhibits neutrophil elastase, leading to unchecked destruction of lung elastin and early-onset emphysema, even in non-smokers [15]. Individuals with the PiZZ phenotype are at particularly high risk.

Having a family history of COPD also increases susceptibility, suggesting a broader genetic predisposition that may interact with environmental exposures [32]. Additionally, certain biological markers, such as elevated levels of eosinophils in blood (≥300 cells/μL), identify a distinct inflammatory phenotype associated with a higher risk of exacerbations and potential responsiveness to inhaled corticosteroids [33].

Other Contributing Factors

Several other factors contribute to the development and progression of COPD. Recurrent respiratory infections during childhood or conditions like uncontrolled asthma can impair lung development and increase vulnerability to COPD in adulthood [34]. Similarly, complications from tuberculosis can lead to chronic airflow obstruction resembling COPD, particularly in regions where TB is endemic [35].

Age is a critical demographic factor, with COPD being more common in individuals over 40 years old, as lung damage accumulates over time [1]. The aging process itself leads to reduced lung elasticity, weaker respiratory muscles, and diminished immune defenses, all of which can exacerbate the effects of COPD [37].

Global and Regional Epidemiology

The global prevalence of COPD is substantial, with estimates suggesting that over 13% of adults in Latin America suffer from the disease [38]. In Spain, while overall prevalence has declined, disparities persist, with a notable increase in cases among women in recent years [39]. The disease burden is particularly high in low-resource settings, where 90% of COPD-related deaths occur, reflecting inequities in healthcare access and exposure to risk factors [40].

Geographic differences are evident between urban and rural areas. In urban settings, outdoor air pollution from traffic and industry is a dominant risk factor, and patients often exhibit higher levels of airway inflammation [41]. Despite greater exposure, urban populations may benefit from better healthcare infrastructure, leading to a "persistent urban advantage" in avoidable mortality [42]. In contrast, rural areas face higher risks from indoor biomass smoke and limited access to diagnostic tools like spirometry, resulting in delayed diagnosis and poorer outcomes [43].

Trends in Disease Burden

Although age-standardized rates of COPD have declined in recent decades, the absolute number of cases, deaths, and disability-adjusted life years (DALYs) continues to rise, especially in regions with aging populations and ongoing exposure to risk factors [44]. This trend is driven by population growth, aging, and persistent environmental exposures. In Colombia, for example, the burden of COPD increased between 2015 and 2022, with a prevalence of 5.13% in 2022 [45].

The rising burden underscores the need for comprehensive public health strategies. In Latin America, the Pan American Health Organization (PAHO) has led efforts to strengthen tobacco control through the Framework Convention on Tobacco Control (FCTC), including tax increases, advertising bans, and smoke-free policies [46]. Uruguay, for instance, reduced smoking rates from 36% in 2005 to 22% in 2022 through rigorous anti-tobacco measures [47].

Public Health Implications

Effective prevention of COPD requires multisectoral action. Policies to reduce air pollution, promote clean cooking technologies, and enforce occupational safety standards are essential. In Costa Rica, the 2025–2028 National Pathway for COPD Management aims to improve early detection, access to treatment, and integrated care [48]. Similarly, the Latin American Thoracic Association (ALAT) has developed evidence-based clinical guidelines to standardize care across the region [49].

In conclusion, the epidemiology of COPD reflects a convergence of behavioral, environmental, and biological risks. While tobacco remains the leading cause, the contribution of air pollution, occupational exposures, and genetic factors is significant, particularly in specific populations. Addressing these risks through coordinated public health initiatives, early detection programs, and equitable access to care is crucial to reducing the global burden of this preventable disease.

Clinical Presentation and Disease Progression

Chronic obstructive pulmonary disease (COPD) is a progressive and irreversible respiratory condition characterized by persistent airflow limitation and chronic inflammation of the airways and lung tissue. The clinical presentation evolves over time, with symptoms worsening as the disease advances, significantly impacting patients' quality of life and functional capacity [1]. Early recognition of symptoms and understanding of disease progression are essential for timely diagnosis and effective management.

Common Symptoms and Initial Signs

The most frequent symptoms of COPD include dyspnea (shortness of breath), chronic cough with sputum production, wheezing (a whistling sound during breathing), fatigue, chest tightness, and increased susceptibility to respiratory infections [51]. In the early stages, symptoms may be mild or even absent, contributing to delayed diagnosis [2]. Dyspnea typically begins during physical exertion and gradually progresses to affect even simple daily activities. Chronic cough with mucus expectoration is often one of the first signs, particularly in individuals with a history of tobacco use [53].

As the disease progresses, additional symptoms may emerge, including weight loss and muscle weakness, especially in advanced stages [51]. The severity and combination of symptoms can vary based on individual factors such as smoking history, exposure to environmental pollutants, and the presence of comorbidities like cardiovascular disease or diabetes mellitus. The chronic nature of these symptoms often leads to reduced physical activity, which can further exacerbate functional decline and contribute to a cycle of deconditioning.

Disease Progression and Functional Decline

COPD is a progressive disease that generally worsens over time if not adequately managed [55]. The hallmark of disease progression is a gradual and persistent decline in lung function, primarily measured by the forced expiratory volume in one second (FEV₁), which reflects the degree of airflow obstruction [56]. This decline is typically more rapid in individuals who continue to smoke or are exposed to other respiratory irritants.

The disease is classified into four stages of severity based on spirometric findings according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) system:

  • Stage 1 (Mild): FEV₁ ≥ 80% of predicted. Many individuals may not experience significant symptoms.
  • Stage 2 (Moderate): FEV₁ between 50% and 79% of predicted. Dyspnea becomes noticeable during exertion.
  • Stage 3 (Severe): FEV₁ between 30% and 49% of predicted. Breathing difficulties are more intense and frequent.
  • Stage 4 (Very Severe): FEV₁ < 30% of predicted, or between 30% and 50% with respiratory failure [57].

This classification helps guide treatment decisions and assess prognosis, although it does not fully capture the impact of symptoms or exacerbation risk on patient outcomes.

Acute Exacerbations and Their Impact

A key feature of COPD progression is the occurrence of acute exacerbations, defined as sudden worsening of respiratory symptoms beyond normal day-to-day variation, requiring a change in medication [58]. These episodes are often triggered by respiratory infections (viral or bacterial), environmental pollutants, or other factors such as non-adherence to treatment. Exacerbations are more common in advanced stages of the disease and are associated with accelerated lung function decline, increased hospitalization rates, and higher mortality [59].

Patients with frequent exacerbations (two or more per year or one requiring hospitalization) are considered at high risk and require more intensive management strategies. The presence of purulent sputum is a strong clinical predictor of bacterial infection and often guides the use of antibiotics during exacerbations [60]. Prompt treatment with bronchodilators, systemic corticosteroids, and, when indicated, antibiotics can help reduce the duration and severity of exacerbations.

Advanced Complications and Systemic Effects

In later stages, COPD can lead to severe complications such as respiratory failure, pulmonary hypertension, and cor pulmonale—a condition where the right side of the heart becomes enlarged due to increased pressure in the pulmonary arteries [59]. These complications significantly affect survival and require specialized interventions, including long-term oxygen therapy for chronic hypoxemia [62].

Beyond the lungs, COPD is associated with systemic inflammation that contributes to various comorbidities, including osteoporosis, depression, and sarcopenia [7]. This systemic involvement underscores the importance of a comprehensive, multidisciplinary approach to patient care, integrating pulmonary rehabilitation, nutritional support, and psychological counseling. Programs such as pulmonary rehabilitation have been shown to improve exercise tolerance, reduce dyspnea, and enhance quality of life, even in patients with advanced disease [64].

The trajectory of COPD is influenced by multiple factors, including smoking cessation, environmental exposures, adherence to treatment, and the presence of comorbidities. While the disease is incurable, interventions such as quitting smoking and appropriate pharmacological therapy with bronchodilators can slow its progression and improve patient outcomes [56]. Understanding the clinical course and anticipating complications allows for proactive management, ultimately helping to preserve function and quality of life in individuals living with COPD.

Diagnosis and Pulmonary Function Testing

The diagnosis of chronic obstructive pulmonary disease (COPD) relies on a comprehensive clinical evaluation combined with objective pulmonary function testing, primarily spirometry. This process aims to confirm persistent airflow limitation, assess disease severity, rule out other respiratory conditions, and guide personalized treatment strategies [66]. Early and accurate diagnosis is crucial for initiating timely interventions that can slow disease progression and improve patient outcomes.

Spirometry: The Cornerstone of COPD Diagnosis

Spirometry is the essential and mandatory diagnostic test for confirming COPD, as it provides an objective measurement of airflow obstruction [67]. The procedure involves the patient taking a deep breath and exhaling forcefully into a spirometer, which records the volume and flow of air expelled. Two key parameters are measured:

  • Forced expiratory volume in one second (FEV₁): the volume of air exhaled in the first second of a forced exhalation.
  • Forced vital capacity (FVC): the total volume of air that can be forcibly exhaled after a full inhalation.

The diagnosis of COPD is confirmed when the post-bronchodilator FEV₁/FVC ratio is less than 0.7. This measurement must be taken after the administration of a short-acting bronchodilator to ensure that the airflow limitation is not fully reversible, which helps differentiate COPD from asthma [68]. The use of post-bronchodilator values increases the specificity of the diagnosis and reduces the likelihood of false positives.

The FEV₁ value, expressed as a percentage of the predicted normal for the patient's age, sex, height, and ethnicity, is used to classify the severity of airflow obstruction according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) system:

  • GOLD 1 (Mild): FEV₁ ≥ 80% of predicted
  • GOLD 2 (Moderate): FEV₁ 50–79% of predicted
  • GOLD 3 (Severe): FEV₁ 30–49% of predicted
  • GOLD 4 (Very Severe): FEV₁ < 30% of predicted [69]

While the fixed ratio of 0.7 is widely used, some experts suggest that age-adjusted lower limits of normal may be more appropriate, particularly in older adults, to avoid overdiagnosis due to physiological aging of the lungs [70]. However, the fixed ratio remains the standard in clinical practice due to its simplicity and reproducibility.

Clinical Evaluation and Patient History

Prior to pulmonary function testing, a thorough clinical assessment is conducted to evaluate symptoms and risk factors. Typical symptoms that raise suspicion for COPD include chronic cough, sputum production, and progressive dyspnea, especially during physical exertion [71]. A detailed history of exposure to respiratory irritants is critical, with tobacco smoking being the most significant risk factor, responsible for over 70% of cases in high-income countries [22]. Other exposures include secondhand smoke, occupational dusts and chemicals, indoor air pollution from biomass fuel combustion, and ambient air pollution.

The clinical evaluation also includes a physical examination to detect signs such as wheezing, prolonged expiratory phase, use of accessory muscles, and signs of hyperinflation. This information, combined with symptom assessment tools like the modified Medical Research Council (mMRC) dyspnea scale or the COPD Assessment Test (CAT), helps contextualize the spirometric findings and assess the impact of the disease on the patient's life.

Complementary Diagnostic Tests

While spirometry is the gold standard, additional tests are often used to complete the diagnostic workup, assess disease extent, and rule out differential diagnoses.

Chest Radiography

A chest X-ray does not diagnose COPD directly but is useful for excluding other conditions such as pneumonia, lung cancer, or heart failure. It may reveal indirect signs of COPD, including:

  • Pulmonary hyperinflation
  • Flattening of the diaphragm
  • Increased anteroposterior diameter of the chest ("barrel chest")
  • Decreased vascular markings in areas of emphysema [73]

Computed Tomography (CT) Scan

High-resolution CT of the chest provides detailed imaging of lung structure and is particularly valuable for evaluating the extent and distribution of emphysema, detecting complications like pneumothorax, and identifying comorbid conditions. It can also reveal incidental findings of COPD in asymptomatic individuals and is used in phenotyping patients for interventions such as lung volume reduction surgery [74].

Arterial Blood Gas Analysis

This test measures the levels of oxygen (PaO₂), carbon dioxide (PaCO₂), pH, and bicarbonate in arterial blood. It is especially indicated in patients with severe symptoms or during acute exacerbations to detect:

  • Hypoxemia (low oxygen levels)
  • Hypercapnia (elevated carbon dioxide levels)
  • Respiratory acidosis
  • Chronic respiratory failure [75]

Additional Pulmonary Function Tests

In select cases, further functional testing may be performed:

  • Body plethysmography: to measure total lung capacity and residual volume, which are often increased in COPD.
  • Diffusing capacity for carbon monoxide (DLCO): useful for assessing alveolar damage, particularly in emphysema, and for differentiating COPD from other obstructive diseases.
  • Exercise testing: such as the 6-minute walk test or cardiopulmonary exercise testing, to evaluate functional capacity and oxygen desaturation during exertion [76].

Differential Diagnosis and Clinical Guidelines

The diagnosis of COPD must be differentiated from other respiratory diseases with overlapping symptoms, including , , , and . The combination of clinical history, spirometry, and imaging helps establish the correct diagnosis [77].

Diagnostic and management decisions are guided by international and national clinical guidelines, such as those from the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the Spanish Guideline for COPD (GesEPOC). These evidence-based recommendations standardize the diagnostic approach, promote early detection, and support individualized patient care [78].

In summary, the diagnosis of COPD is confirmed by post-bronchodilator spirometry showing an FEV₁/FVC ratio < 0.7. This is supported by a comprehensive clinical evaluation, patient history, and complementary tests such as chest imaging, arterial blood gases, and advanced pulmonary function studies. Adherence to established guidelines ensures accurate diagnosis, appropriate classification, and effective management planning.

Classification and Severity Assessment

The classification and severity assessment of chronic obstructive pulmonary disease (COPD) is a critical component in guiding clinical management and treatment strategies. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) system is the internationally recognized standard for categorizing the severity of COPD, integrating both functional and clinical parameters to provide a comprehensive evaluation of disease burden [3].

Functional Classification Based on Spirometry

The cornerstone of COPD severity classification is spirometry, a pulmonary function test that objectively measures airflow limitation. The diagnosis of COPD is confirmed when the post-bronchodilator ratio of forced expiratory volume in one second (FEV₁) to forced vital capacity (FVC) is less than 0.70 [80]. This fixed ratio is used to define persistent airflow obstruction, distinguishing COPD from other respiratory conditions such as asthma, where airflow limitation is typically reversible.

The severity of airflow obstruction is primarily classified according to the percentage of predicted FEV₁, which reflects the degree of pulmonary impairment. The GOLD system divides this into four grades:

  • GOLD 1 (Mild): FEV₁ ≥ 80% of predicted value
  • GOLD 2 (Moderate): 50% ≤ FEV₁ < 80% of predicted
  • GOLD 3 (Severe): 30% ≤ FEV₁ < 50% of predicted
  • GOLD 4 (Very Severe): FEV₁ < 30% of predicted or FEV₁ between 30–50% with chronic respiratory failure [3]

While FEV₁ remains a key predictor of morbidity and mortality, it does not fully capture the clinical heterogeneity of COPD. Therefore, the GOLD guidelines have evolved to incorporate additional clinical dimensions beyond spirometry alone.

Multidimensional Clinical Assessment: The GOLD ABCD and ABE Systems

To address the limitations of spirometry-based classification, GOLD introduced a multidimensional approach that combines functional status with symptom burden and exacerbation risk. Historically, this was structured as the ABCD assessment, but recent updates, particularly GOLD 2026, have transitioned to a simplified ABE classification that better reflects patient outcomes and therapeutic needs [82].

This system evaluates two main domains:

  1. Symptom Burden: Assessed using validated questionnaires such as the Modified Medical Research Council (mMRC) dyspnea scale or the COPD Assessment Test (CAT). Patients with mMRC ≥ 2 or CAT ≥ 10 are considered to have high symptom burden.
  2. Exacerbation Risk: Determined by the history of exacerbations in the past year. A patient is classified as high risk if they have experienced two or more mild exacerbations or one or more hospitalizations due to exacerbation [83].

Based on these criteria, patients are assigned to one of three groups:

  • Group A: Low symptoms, low exacerbation risk
  • Group B: High symptoms, low exacerbation risk
  • Group E: High exacerbation risk (regardless of symptom level)

The elimination of the former Group C (low symptoms, high risk) reflects evidence that patients with high exacerbation risk have similar prognoses and benefit from more intensive therapy, irrespective of symptom severity [82].

Integration of Additional Clinical Factors in Severity Assessment

Beyond spirometry and the ABE framework, several other factors are essential for a complete severity assessment and therapeutic decision-making:

  • Comorbidities: Conditions such as cardiovascular disease, diabetes, osteoporosis, and depression are common in COPD and influence prognosis and treatment choices. For example, the use of inhaled corticosteroids must be weighed against the increased risk of pneumonia and bone loss in patients with relevant comorbidities [3].
  • Phenotypic Characterization: Identifying clinical phenotypes—such as the chronic bronchitis phenotype (chronic cough and sputum production) or the emphysema phenotype (progressive dyspnea and hyperinflation)—helps tailor interventions. Patients with emphysema may benefit from lung volume reduction techniques, while those with chronic bronchitis might respond to therapies like roflumilast, a phosphodiesterase-4 inhibitor [86].
  • Biomarkers: Blood eosinophil count is a crucial biomarker for guiding therapy. A count ≥300 cells/μL identifies patients with an eosinophilic inflammatory phenotype who are more likely to benefit from corticosteroid therapy and biologic agents such as benralizumab [21].
  • Functional Capacity: Tools such as the 6-minute walk test and daily activity monitoring provide insight into real-world functional impairment and help assess the impact of disease beyond spirometry [88].

Implications for Therapeutic Management

The severity classification directly informs treatment algorithms. For instance:

  • Group A patients may be managed with short- or long-acting bronchodilators as needed.
  • Group B patients typically require long-acting bronchodilators (LABA or LAMA), with dual therapy (LABA/LAMA) considered if symptoms persist.
  • Group E patients, due to their high risk of exacerbations, often require dual or triple therapy (LABA/LAMA/ICS), especially if eosinophil counts are elevated [89].

This personalized approach ensures that therapy is aligned with the patient’s clinical profile, maximizing efficacy while minimizing unnecessary treatment and adverse effects.

In summary, the classification and severity assessment of COPD has evolved from a purely spirometry-based model to a multidimensional framework that integrates functional, symptomatic, and clinical risk factors. The GOLD ABE system, supported by phenotypic and biomarker data, enables a more precise and individualized approach to managing this complex and heterogeneous disease. Regular reassessment is recommended to adapt treatment as the disease progresses or the patient’s risk profile changes.

Pharmacological Management

The pharmacological management of chronic obstructive pulmonary disease (COPD) is a cornerstone of treatment, aimed at reducing symptoms, preventing exacerbations, improving quality of life, and slowing disease progression. Treatment is highly individualized, guided by clinical guidelines such as those from the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the Guía Española de la EPOC (GesEPOC), and tailored to the patient's symptom burden, risk of exacerbations, and functional status [3].

Bronchodilators: The Foundation of Maintenance Therapy

Bronchodilators are the primary pharmacological agents used in COPD, working by relaxing airway smooth muscle to reduce airflow obstruction and improve ventilation. They are classified based on duration of action into short-acting and long-acting formulations.

Short-acting bronchodilators, including short-acting beta-2 agonists (SABA) like salbutamol and short-acting muscarinic antagonists (SAMA) like ipratropio, are used on an as-needed basis for acute symptom relief. These medications provide rapid onset of action and are essential during exacerbations or periods of increased dyspnea [86].

Long-acting bronchodilators are the mainstay of maintenance therapy for patients with persistent symptoms. Long-acting beta-2 agonists (LABA), such as formoterol and vilanterol, and long-acting muscarinic antagonists (LAMA), such as tiotropio and umeclidinio, offer sustained bronchodilation over 12 to 24 hours. LAMAs are particularly effective in reducing hyperinflation and preventing exacerbations, while LABAs significantly improve lung function and exercise tolerance [92].

Combination therapy with LABA/LAMA has demonstrated superior efficacy compared to monotherapy, with greater improvements in lung function, symptom control, and reduction in exacerbations and hospitalizations. This dual bronchodilation approach is recommended as first-line therapy for patients with moderate to severe symptoms or a history of exacerbations [93].

Inhaled Corticosteroids and Combination Therapies

Inhaled corticosteroids (ICS) are not recommended as monotherapy for COPD due to lack of mortality benefit and potential risks, including pneumonia and osteoporosis. However, they play a critical role in combination with bronchodilators for specific patient subgroups.

The use of ICS in combination with LABA (LABA/ICS), such as fluticasona/salmeterol or budesonida/formoterol, is indicated for patients with frequent exacerbations (≥2 moderate or ≥1 severe exacerbation requiring hospitalization in the past year) and elevated blood eosinophil counts (≥100 cells/µL). This combination reduces the frequency of exacerbations by targeting underlying airway inflammation [33].

For patients who continue to experience exacerbations despite dual bronchodilator therapy, triple therapy—combining LABA, LAMA, and ICS—is recommended. Fixed-dose combinations such as furoato de fluticasona/umeclidinio/vilanterol (Trelegy Ellipta) offer improved adherence and have been shown to further reduce exacerbation rates, particularly in patients with eosinophilic inflammation (blood eosinophils ≥300 cells/µL) [95]. However, the benefits must be weighed against the increased risk of adverse effects, including oral candidiasis, pneumonia, and bone fractures [96].

Targeted Therapies Based on Clinical Phenotypes

Treatment selection is increasingly guided by clinical phenotypes, which reflect different patterns of disease expression and response to therapy.

Patients with a chronic bronchitis phenotype, characterized by chronic cough and sputum production, may benefit from the addition of roflumilast, a phosphodiesterase-4 (PDE4) inhibitor. Roflumilast reduces exacerbations in patients with severe COPD and chronic bronchitis, particularly those with a history of frequent exacerbations [97]. It is often used as an adjunct to bronchodilators and ICS in this subgroup.

In patients with emphysema-predominant disease, interventions such as endobronchial valves or lung volume reduction surgery may be considered in select cases, although pharmacological management remains foundational. For those with alpha-1 antitrypsin deficiency (AATD), a genetic cause of early-onset emphysema, specific therapy with intravenous augmentation of alpha-1 antitrypsin (e.g., Prolastin®-C) is available. This treatment aims to restore protective serum levels of AAT and slow lung tissue destruction [98].

The asthma-COPD overlap (ACO) phenotype, where patients exhibit features of both diseases, typically responds well to ICS-containing regimens. Initial treatment often includes LABA/ICS, with escalation to triple therapy if symptoms or exacerbations persist [99].

Emerging and Adjunctive Pharmacological Approaches

Research into novel therapies continues to expand the pharmacological armamentarium for COPD. Biologic therapies targeting type 2 inflammation, such as benralizumab (an anti-IL-5 receptor alpha monoclonal antibody), are being evaluated in clinical trials for patients with eosinophilic COPD. The ABRA trial, a randomized, double-blind, placebo-controlled study, is investigating the efficacy of benralizumab in reducing eosinophilic exacerbations in patients with COPD and asthma [21].

Other investigational approaches include gene editing for AATD, with companies like Beam Therapeutics developing BEAM-302 and Tessera Therapeutics advancing TSRA-196, both aiming to correct the underlying genetic defect [101]. These therapies represent a potential shift from symptomatic management to disease modification.

Adjunctive oral medications such as azithromycin, a macrolide antibiotic with immunomodulatory properties, may be used in select patients with frequent exacerbations who remain symptomatic despite optimal inhaled therapy. Long-term use requires careful monitoring for side effects, including hearing loss and QT prolongation [102].

Treatment De-escalation and Monitoring

Pharmacological management should be dynamic, with regular reassessment of symptom control, exacerbation history, and eosinophil levels. In stable patients with low exacerbation risk and low eosinophil counts, de-escalation of therapy—such as withdrawing ICS from triple therapy—may be considered to minimize side effects while maintaining disease control [103].

Regular monitoring includes assessment of inhaler technique, adherence, and response to therapy using tools such as the COPD Assessment Test (CAT) and modified Medical Research Council (mMRC) dyspnea scale. Spirometry remains essential for evaluating lung function over time [86].

In summary, pharmacological management of COPD is a personalized, evolving process that integrates bronchodilators as the foundation, adds ICS for patients with eosinophilic inflammation or frequent exacerbations, and tailors therapy to clinical phenotypes. Emerging biologics and gene-based therapies hold promise for more targeted, effective treatments in the future.

Non-Pharmacological Interventions and Rehabilitation

Non-pharmacological interventions are essential components in the comprehensive management of chronic obstructive pulmonary disease (COPD), complementing pharmacological therapies to improve symptoms, reduce exacerbations, enhance functional capacity, and significantly increase quality of life. These strategies address the multifactorial nature of COPD by targeting physical, psychological, and social aspects of the disease. Key non-pharmacological approaches include pulmonary rehabilitation, smoking cessation, physical activity, nutritional support, and vaccination, all of which are supported by robust clinical evidence and recommended in international guidelines such as those from the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the Guía Española de la EPOC (GesEPOC).

Pulmonary Rehabilitation: Core of Non-Pharmacological Management

Pulmonary rehabilitation (PR) is a structured, multidisciplinary intervention considered a cornerstone in the management of symptomatic COPD patients, particularly those in GOLD groups B and E. It is strongly recommended for individuals with persistent symptoms, functional limitations, or a history of exacerbations, regardless of the severity of airflow obstruction measured by FEV1 [3]. PR is not limited to patients with advanced disease; it benefits individuals across the spectrum of COPD severity who experience breathlessness or reduced exercise tolerance.

The core of PR is supervised physical training, which includes aerobic exercises such as walking or cycling, and resistance training for both upper and lower limbs. This training improves muscle strength and endurance, enhances exercise capacity, and reduces the sensation of dyspnea. The benefits are typically measured using the six-minute walk test, a reliable indicator of functional improvement [106]. Programs usually last 6 to 12 weeks, with studies showing that 8- to 12-week regimens produce significant improvements in exercise tolerance, dyspnea, and quality of life, with effects that can be sustained through supervised maintenance programs [107].

Essential Components of Pulmonary Rehabilitation Programs

Pulmonary rehabilitation is more than just exercise; it is a comprehensive program that integrates several essential components to empower patients and improve long-term outcomes.

Therapeutic Education and Self-Management

Education is a fundamental pillar of PR. Patients receive training on the pathophysiology of COPD, the correct use of inhalation devices, strategies for energy conservation, and techniques to control dyspnea, such as pursed-lip breathing and diaphragmatic breathing [108]. Recognizing early signs of exacerbation and knowing how to respond using personalized action plans are critical skills that reduce emergency visits and hospitalizations [109].

Psychological Support and Comorbidity Management

Anxiety and depression are highly prevalent in COPD and significantly impact quality of life and treatment adherence. Psychological interventions, including cognitive-behavioral therapy and support groups, are integral to PR programs. Addressing these mental health issues improves patient engagement and overall well-being [106].

Nutritional Assessment and Smoking Cessation

Nutritional status is closely linked to respiratory health. Both undernutrition and obesity can impair respiratory muscle function and exercise capacity. A nutritional evaluation and personalized dietary advice are therefore crucial, especially for patients with weight loss or muscle wasting [64]. Furthermore, for patients who continue to smoke, integrating a structured smoking cessation program into PR is a priority, as quitting remains the most effective intervention to slow disease progression [112].

Maintenance and Long-Term Adherence

The benefits of PR can diminish without continued effort. Supervised maintenance programs have been shown to be more effective than usual care in preserving the gains achieved during the initial rehabilitation phase [113]. These programs ensure long-term adherence to physical activity and self-management practices.

Smoking Cessation and Lifestyle Modifications

Smoking cessation is the single most effective non-pharmacological intervention for altering the natural history of COPD. It slows the accelerated decline in lung function and reduces the risk of exacerbations and mortality. Support for quitting should include behavioral counseling, pharmacological aids such as nicotine replacement therapy, varenicline, or bupropion, and follow-up to prevent relapse [114].

Regular physical activity, even outside formal PR, is vital. It helps maintain muscle strength, improves cardiovascular health, and enhances overall well-being. Patients are encouraged to engage in daily activities tailored to their capabilities, with guidance from healthcare providers [115].

Vaccination and Preventive Strategies

Vaccination plays a key role in preventing exacerbations triggered by respiratory infections. Annual influenza vaccination and pneumococcal vaccination (preferably with the 13-valent conjugate vaccine, PCV13) are strongly recommended for all COPD patients, particularly the elderly, to reduce the incidence of pneumonia, hospitalizations, and mortality [116]. Vaccination against SARS-CoV-2 is also essential, given the increased risk of severe outcomes in this population [117].

Implementation and Accessibility

Pulmonary rehabilitation can be delivered in outpatient, inpatient, home-based, or hybrid models, increasing accessibility, especially in areas with limited healthcare resources [106]. Integration of PR into primary care and the use of telehealth technologies are promising strategies to expand access and ensure continuity of care. National initiatives, such as the National Pathway for COPD Management in Costa Rica, aim to standardize and improve the delivery of comprehensive care, including rehabilitation, across health systems [48].

In conclusion, non-pharmacological interventions, with pulmonary rehabilitation at the forefront, are indispensable in the holistic management of COPD. These strategies, when systematically implemented, lead to measurable improvements in patient-centered outcomes, reduce the burden of the disease on healthcare systems, and are a testament to the power of integrated, patient-focused care.

Exacerbation Management and Hospitalization Criteria

An acute exacerbation of chronic obstructive pulmonary disease (COPD) is defined as a sustained worsening of respiratory symptoms beyond normal day-to-day variation, requiring a change in medication. Effective management of these episodes is crucial to alleviate symptoms, prevent complications, reduce hospitalization rates, and improve long-term outcomes. Treatment strategies are tailored based on the severity of the exacerbation and may include bronchodilators, systemic corticosteroids, antibiotics, oxygen therapy, and non-invasive ventilation [120].

Pharmacological Interventions

Bronchodilators

Short-acting bronchodilators are the cornerstone of initial treatment during an exacerbation. These medications, including short-acting beta-2 agonists (SABA) like salbutamol and short-acting muscarinic antagonists (SAMA) such as ipratropium, help relieve bronchospasm and improve airflow. They are typically administered via nebulizer or metered-dose inhaler with a spacer, allowing for rapid symptom relief [120]. The use of combination therapy (SABA + SAMA) has been shown to provide greater bronchodilation than either agent alone.

Systemic Corticosteroids

Systemic corticosteroids play a vital role in reducing airway inflammation during acute exacerbations. Oral prednisone at a dose of 30–40 mg/day for 5 to 7 days is recommended, as it improves lung function, shortens recovery time, and reduces the risk of treatment failure and relapse [122]. Evidence supports that shorter courses are as effective as longer ones, minimizing the risk of adverse effects such as hyperglycemia, myopathy, and psychiatric disturbances [123].

Antibiotics

Antibiotics are indicated when there is clinical suspicion of bacterial infection, which is a common trigger for exacerbations. Their use should be guided by specific criteria: an increase in two or three cardinal symptoms—dyspnea, sputum volume, and sputum purulence—with the presence of purulent sputum being the strongest predictor of bacterial etiology [60]. Patients with more severe disease (GOLD groups C and D), frequent exacerbations, or underlying bronchiectasis have a lower threshold for antibiotic initiation. Commonly prescribed agents include amoxicillin-clavulanate, doxycycline, or macrolides, depending on local resistance patterns and patient factors.

Oxygen Therapy and Ventilation Support

Oxygen Therapy

Controlled oxygen therapy is essential for patients experiencing hypoxemia during an exacerbation. The target oxygen saturation should be maintained between 88% and 92% to avoid the risk of hypercapnia and respiratory acidosis, particularly in patients with a history of chronic carbon dioxide retention [125]. Oxygen should be delivered at low flow rates (1–2 L/min) initially and titrated based on pulse oximetry or arterial blood gas analysis. Uncontrolled oxygen administration can suppress the hypoxic drive to breathe, leading to worsening hypercapnia and potential respiratory failure [126].

Non-Invasive Ventilation (NIV)

Non-invasive ventilation (NIV) is a life-saving intervention for patients with acute respiratory failure due to COPD exacerbation. It is particularly effective in those with persistent hypercapnia and acidosis despite optimal medical therapy. Indications for NIV include arterial pH < 7.35 and PaCO₂ > 50 mmHg, along with signs of respiratory distress or fatigue [127]. The preferred mode is bilevel positive airway pressure (BiPAP), which provides different levels of pressure during inspiration (IPAP) and expiration (EPAP), improving alveolar ventilation and reducing work of breathing. NIV has been shown to decrease the need for endotracheal intubation, reduce mortality, and shorten hospital stays [127]. Continuous monitoring of clinical status and blood gases is essential to assess response and detect early signs of NIV failure, which may necessitate invasive mechanical ventilation [129].

Criteria for Hospital Admission

Decisions regarding hospitalization are based on a combination of clinical, functional, and social factors. Early identification of high-risk patients ensures timely access to intensive care and prevents adverse outcomes.

Clinical Indicators

Hospital admission is warranted in the presence of any of the following:

  • Acute respiratory failure, evidenced by severe hypoxemia or hypercapnia
  • Arterial pH < 7.35 indicating respiratory acidosis
  • Altered mental status such as confusion or somnolence, suggestive of severe hypercapnia
  • Inadequate response to outpatient treatment
  • Presence of significant comorbidities such as heart failure, arrhythmias, or chronic kidney disease that could complicate management [130]

Functional and Social Factors

Beyond clinical parameters, functional and social determinants also influence admission decisions:

  • Lack of adequate support at home
  • Difficulty adhering to complex treatment regimens
  • Limited access to healthcare services or emergency resources
  • History of frequent exacerbations or prior hospitalizations for COPD [131]

Additional Risk Factors

Other factors that increase the likelihood of hospitalization include:

  • Advanced age
  • Severe airflow limitation (FEV₁ < 30% of predicted)
  • Coexisting conditions such as bronchiectasis or pulmonary hypertension [132]

Post-Exacerbation Management

Following stabilization, post-exacerbation care is critical to prevent recurrence and improve long-term outcomes. Pulmonary rehabilitation should be initiated as soon as possible, ideally within four weeks of discharge. This structured program includes supervised exercise training, patient education, nutritional counseling, and psychological support. Evidence shows that early rehabilitation significantly improves exercise tolerance, reduces dyspnea, enhances quality of life, and lowers the risk of rehospitalization [133].

Vaccination status should be reviewed and updated, with annual influenza and pneumococcal vaccines strongly recommended to prevent future respiratory infections. Additionally, optimization of maintenance therapy, including the use of long-acting bronchodilators and inhaled corticosteroids in appropriate phenotypes, helps reduce the frequency and severity of subsequent exacerbations. Regular follow-up in primary care or by a specialist ensures ongoing monitoring and adjustment of treatment plans.

Public Health Strategies and Prevention

Chronic obstructive pulmonary disease (COPD) is a largely preventable condition, and public health strategies play a crucial role in reducing its global burden. These strategies focus on primary prevention through the control of major risk factors, early detection, and the implementation of population-level interventions to reduce exposure to lung irritants. Key organizations such as the World Health Organization and the Pan American Health Organization have led coordinated efforts, particularly in regions with high disease prevalence like Latin America and the Caribbean.

Tobacco Control: The Cornerstone of Prevention

Tobacco use remains the leading cause of COPD, responsible for over 70% of cases in high-income countries and a significant proportion in Latin America [1]. Comprehensive tobacco control policies are therefore fundamental to primary prevention. The Framework Convention on Tobacco Control (FCTC), adopted by the WHO, provides a roadmap for effective interventions, including tax increases on tobacco products, comprehensive bans on advertising, promotion, and sponsorship, implementation of plain packaging, and the creation of 100% smoke-free public spaces [46].

Countries like Uruguay have demonstrated the success of such policies, reducing adult smoking prevalence from 36% in 2005 to 22% in 2022 through strict regulations and public awareness campaigns [47]. In 2024, the WHO released its first-ever clinical guidelines for tobacco cessation in adults, emphasizing combined behavioral counseling and pharmacological support (e.g., varenicline, nicotine replacement therapy) as the most effective approach [114]. Reducing secondhand smoke exposure is also critical, as it increases the risk of developing COPD, particularly in non-smoking women and children [138].

Reducing Environmental and Occupational Exposures

Beyond tobacco, public health initiatives must address other significant sources of lung damage. Indoor air pollution from the use of biomass fuels (wood, charcoal, agricultural waste) for cooking and heating is a major risk factor in low- and middle-income countries, contributing to 30–40% of COPD cases in these regions [1]. The WHO advocates for the transition to clean cooking technologies and improved home ventilation to mitigate this risk [140].

Outdoor air pollution, including particulate matter (PM2.5, PM10), nitrogen dioxide (NO₂), and ozone, is also strongly linked to the development and worsening of COPD [27]. Public policies promoting sustainable transportation, regulating industrial emissions, and monitoring air quality are essential for population health. Occupational exposure to dusts (e.g., silica, coal), vapors, and chemical fumes in industries like mining, construction, and agriculture accounts for an estimated 15–20% of COPD cases in Spain and is a significant concern in Latin America [28]. Strengthening occupational health and safety regulations, providing protective equipment, and conducting epidemiological surveillance are key preventive measures.

Early Detection and Screening Programs

Despite the availability of effective diagnostic tools, COPD remains significantly underdiagnosed, with up to 75% of cases undetected in countries like Spain [143]. This is particularly problematic in older adults, where symptoms are often mistaken for normal aging. The gold standard for diagnosis, spirometry, is underutilized in primary care due to limited access to equipment and trained personnel [144].

To address this, targeted screening programs in high-risk populations—such as current or former smokers over 40 years of age or those with occupational exposures—are being promoted. The PUMA study in Latin America demonstrated the effectiveness of a strategy combining a validated electronic risk questionnaire with confirmatory spirometry in primary care, significantly increasing case detection [145]. National clinical pathways, such as Costa Rica's 2025 National Route for COPD Management, aim to standardize early detection and improve care coordination [48].

Patient Education and Self-Management

Educating patients about COPD, its risk factors, and self-care is a vital component of public health strategy. Structured education programs in primary care, delivered through group workshops or individual sessions, have been shown to improve inhaler technique, enhance adherence to treatment, and empower patients to recognize and manage exacerbations early [147]. These programs often include training in breathing techniques (e.g., pursed-lip breathing), energy conservation, and the use of personalized action plans, which can reduce hospitalizations and improve quality of life [148].

Vaccination as a Preventive Measure

Vaccination is a critical intervention for preventing exacerbations, which are often triggered by respiratory infections. Annual influenza vaccination and pneumococcal vaccination (preferably with the 13-valent conjugate vaccine, PCV13) are strongly recommended for all COPD patients, especially older adults [149]. Evidence shows these vaccines reduce the incidence of respiratory infections, pneumonia, hospitalizations, and mortality [116]. The ALAT (Latin American Thoracic Association) guidelines reinforce the importance of these vaccinations as part of comprehensive COPD management [49].

Challenges and Future Directions

Despite progress, significant challenges remain, including disparities in policy implementation, pressure from the tobacco industry, and limited resources for sustained cessation programs and air quality monitoring [46]. Future efforts must focus on equitable access to preventive services, the integration of COPD management into primary care, and the adoption of innovative strategies such as telemonitoring and mobile health applications to support patient self-management [153]. By addressing these challenges, public health strategies can continue to reduce the incidence and impact of COPD worldwide.

References